Generally, a conventional faucet includes a faucet body, and after processing and manufacturing, at least a chamber and a flow channel are formed and settled inside the faucet body to provide an accommodating space for the valve cartridge thereby controlling water flowing of the faucet. However, this kind of the faucet has its shortcomings such as the difficulty of processing and manufacturing, and during the assembling process, a control valve of the faucet and other components need to be settled inside the faucet in sequence thereby increasing the difficulty of the assembly and the cost of time and money. Moreover, because of the complexity in structure, the valve cartridge of the faucet cannot be quickly replaced by a general user, thus reducing the practicability of the faucet. Also, although the general user knows that the damage to the valve cartridge or wear to O-rings of the faucet is the main factor in leakage water or reduced water output, it is still difficult for the general user to dismantle and replace the valve cartridge or other components inside the faucet because of the complexity of the faucet structure. As a result, the user may directly replace the whole faucet thereby increasing the cost of replacing. Therefore, there remains a need for a new and improved design for a faucet with a quickly replaceable valve cartridge to overcome the problems presented above.